1. Field of the Invention
The present invention relates to an exercise machine. In particular, the present invention relates to an exercise sit up machine which positions the user to emphasize the development and exercise of the user's abdominal muscles without emphasizing the development and exercise of the user's back and hip muscles.
2. Description of the Prior Art
Sit ups are traditionally done to exercise and develop a person's abdominal muscles. Sit ups may be done in a number of positions. Sit ups may be done on an inclined surface with the person's head at a position which is vertically lower than the position of his or her feet. However, sit ups done from this position tend to exercise and develop the person's back and hip muscles more than exercising and developing the abdominal muscles. This is because the back and hip muscles are predominantly used to overcome the force of gravity to raise his or her upper body from this position.
When sit ups are done by lying flat on a board or on the ground, the person's head is at the same vertical level as his or her feet. Sit ups may also be done on an inclined surface with the person's head at a position vertically above the feet. Sit ups done from these two positions do not require the person to use additional force to overcome the gravitational force in raising his or her upper body. More importantly, the back and hip muscles do not play such a major role in lifting the upper body. This allows the abdominal muscles to be properly exercised and developed.
Furthermore, therapy for patients suffering from back injuries often include the strengthening of the abdominal muscles because stronger abdominal muscles help the body to support the back and relieves the stress experienced by the back. Accordingly, sit ups done on an inclined surface with the patient's head at a position vertically above the feet are effective in helping such patients strengthen their abdominal muscles without straining their back muscles.
The exercise machines currently available generally allow the user to perform sit ups, if at all, either on a flat board or with the user's head at a position vertically below the feet. An example of such an exercise machine is described in U.S. Pat. No. 4,512,572 to Hamm, which may be vertically inclined for a user to perform sit ups in positions where the user's feet are at a higher vertical position than the user's head. Each of these machines has the disadvantage that they over-exercise and over-develop the user's back and hip muscles.
Many of these prior art exercise machines are programmable in that they are connected to a computer to electronically control the operation of the machines to facilitate different exercise routines. However, none of these prior art machines calculate and display a score for sit up routines performed by the user.